Ball valve

ABSTRACT

A ball valve comprises a housing, a ball seat arranged in the housing and a ball member mounted within the housing and being rotatable relative to the ball seat between open and closed positions. The ball seat and ball member define respective through bores each having a bore edge, wherein the bore edge of at least one of the valve seat and ball member defines a recessed cutting region for cutting a body extending at least partially through the valve upon closure of the ball member.

FIELD OF THE INVENTION

The present invention relates to a ball valve configured for shearing a body upon closure. The present invention in particular, but not exclusively, relates to a ball valve for use in a landing string arrangement, for example for use within a subsea test tree.

BACKGROUND TO THE INVENTION

Landing strings are used in the oil and gas industry for through-riser deployment of equipment, such as completion architecture, well testing equipment, intervention tooling and the like into a subsea well from a surface vessel. When in a deployed configuration the landing string extends between the surface vessel and the wellhead, for example a wellhead Blow Out Preventor (BOP). While deployed the landing string provides many functions, including permitting the safe deployment of wireline or coiled tubing equipment through the landing string and into the well, providing the necessary primary well control barriers and permitting emergency disconnect while isolating both the well and landing string.

Wireline or coiled tubing deployment may be facilitated via a lubricator valve which is located proximate the surface vessel, for example below a rig floor.

Well control and isolation in the event of an emergency disconnect is provided by a suite of valves, typically ball valves, which are located at a lower end of the landing string, normally positioned inside the central bore of the BOP. The valve suite includes a lower valve assembly called the subsea test tree (SSTT) which provides a safety barrier to contain well pressure, and an upper valve assembly called the retainer valve which isolates the landing string contents and can be used to vent trapped pressure from between the retainer valve and SSTT. A shear sub component extends between the retainer valve and SSTT which is capable of being sheared by the BOP if required.

As noted above, the landing string may accommodate wireline and/or coiled tubing deployed tools. In this respect the various valve assemblies, such as in the SSTT, must define sufficiently large internal diameters to permit unrestricted passage therethrough. However, the valve assemblies also have outer diameter limitations, for example as they must be locatable within the wellhead BOP. Such conflicting design requirements may create difficulty in, for example, achieving appropriate valve sealing, as increasing the internal diameter within a restricted outer diameter may only permit minimal a sealing area to be provided.

Furthermore, the landing string must be capable of cutting any wireline or coiled tubing which extends therethrough in the event of an emergency disconnect. It is known in the art to use one or more of the valves to shear through the wireline or coiled tubing upon closure. However, providing a valve with the necessary cutting capacity may be difficult to achieve within the geometric design constraints associated with the landing string. For example, the valve actuators must be of sufficient size to provide the necessary closing/cutting forces, which may be difficult to accommodate within the restricted available size.

Furthermore, in ball valve applications a ball is provided with a throughbore, wherein an edge of the throughbore functions to cut through wireline or coiled tubing upon rotation of the ball towards a closed configuration. Known ball valve designs are such that the throughbore is circular providing a correspondingly shaped throughbore edge. The present inventors have discovered that, particularly with coiled tubing, the cutting forces are applied initially centrally of the tubing, causing the tubing to collapse, making subsequent shearing of the collapsed tube difficult and energy/force intensive.

The landing string must also be designed to accommodate the significant in-service loadings, such as the global tension from a supported lower string (e.g., a test string, completion or the like), bending loads, valve actuation loading, internal and external pressures and the like. As the industry continues to move into fields with increasing formation and water depths, the resulting structural demands on the landing string also become more extreme. For example, landing string global tension requirements far in excess of 4.5 MN (1,000,000 lbf) and wellbore pressures which can exceed 690 bar (10,000 psi) are typical. Such loadings must be accommodated across regions including the various valve assemblies, such as the SSTT. It is therefore necessary to design the valve housings and appropriate end connections to be capable of accommodating the global applied tension, bending loads, valve actuation loading and pressures. This results in the use of thick walled valve housings, which can compromise the achievable valve internal diameters and sealing integrity. Furthermore, current industry standards call for all connections through such landing string valve assemblies to be configured to avoid separation during use to improve fatigue performance. Such connections may include bolted connections of the valve housings into the landing string. This typically requires significant upsizing of the connections and establishes further difficulties in achieving sufficiently large internal diameters within the outer diameter constraints, such as dictated by the BOP.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention there is provided a ball valve comprising:

-   -   a housing;     -   a ball seat arranged in the housing;     -   a ball member mounted within the housing and being rotatable         relative to the ball seat between open and closed positions;     -   wherein the ball seat and ball member define respective through         bores each having a bore edge, and wherein the bore edge of at         least one of the valve seat and ball member defines a recessed         cutting region for cutting a body extending at least partially         through the valve upon closure of the ball member.

The respective through bores of the ball seat and ball member may define a flow path through the valve. The ball member may be rotated relative to the ball seat to misalign the respective through bores to prevent or restrict flow through the valve, and may be rotated relative to the ball seat to align, for example coaxially align, the respective through bores to permit or increase flow through the valve.

In use, closure of the ball member to prevent or restrict flow through the valve may also result in any body which at least partially extends through the valve being cut, for example partially or fully cut. This arrangement may permit full closure of the valve member to be achieved without impedance from the body.

The ball valve may have numerous applications as might readily be understood by those of skill in the art. In some embodiments the ball valve may be configured for use within a landing string assembly. For example, the ball valve may define or form part of a Subsea Test Tree (SSTT), a retainer valve, a lubricator valve or the like.

A recessed cutting region may be configured to cut an elongate body, such as tubing, coiled tubing, wireline, slickline, a tool string or the like. A recessed cutting region may be configured to cut, for example effectively cut, a generally circular body. The body may extend at least partially through the respective through bores of the ball seat and ball member. The body may extend entirely through the respective through bores of the ball seat and ball member. In such arrangements the through bores of the ball seat and ball member may be configured to accommodate a body to extend at least partially therethrough.

Both the ball seat and ball member may define a recessed cutting region. In such an arrangement the respective recessed cutting regions may be configured similarly, or differently. Respective recessed cutting regions of the ball seat and ball member may be generally aligned with each other. Such alignment may be considered to exist in a plane which is perpendicular to a rotational axis of the ball member. In other embodiments the respective recessed cutting regions of the ball seat and ball member may be misaligned.

Only one of the ball seat and ball member may define a recessed cutting region. This arrangement may be advantageous in that the component which does not comprise a cutting recess may hold the body being cut in a more central position relative to the ball seat and ball member, presenting the body in a better position to be cut. In one embodiment only the ball member may define a recessed cutting region.

A recessed cutting region may be recessed relative to an associated through bore. That is, the recessed cutting region may be outwardly recessed relative to an associate throughbore.

A recessed cutting region may be configured to at least partially receive a body to be cut. The recessed cutting region may be configured to entirely receive a body to be cut. In some embodiments, large bodies, for example large diameter bodies may only partially be received within the recessed cutting region.

A recessed cutting region may be provided in a leading edge of one or both of the ball seat and ball member. In this respect the leading edges of the ball seat and ball member may be considered to be those edges of the respective through bores which initially pass each other upon closure of the ball member relative to the seat.

Upon closure of the ball member the bore edge of the ball member throughbore may engage and displace a body which at least partially extends through the valve until said body is engaged between the ball member bore edge and the ball seat bore edge and at least partially received within a recessed cutting region, such that further rotational movement of the ball member towards a closed position permits cutting of the body, typically by a shearing action, by the recessed cutting region.

A recessed cutting region may define a cutting edge. The cutting edge may be formed continuously with the edge of an associated through bore edge.

A recessed cutting region may define at least two cutting edges configured to permit simultaneous cutting into separate regions of a body, for example upon initial contact with the body. A recessed cutting region may be arranged to define at least two points of cutting contact with a body during cutting thereof. During initial contact with the body during cutting thereof the at least two points of cutting contact may be offset from a central region of the body. During initial contact with the body the at least two points of cutting contact may be offset from a central region of the recessed cutting region. This arrangement may permit the force of cutting to be divided between the different points of cutting contact, assisting to prevent adverse compression, collapsing or the like of the body. Furthermore, this arrangement may prevent large cutting forces being applied initially centrally of a body which may assist to prevent collapse of the body, for example. Also, this arrangement may require less torque through the ball member to cut the body. Such reduced loading is anticipated to reduce damage to the components of the ball valve which may assist in preventing or reducing any damage to sealing regions. During cutting of a body, the at least two points of cutting contact with the body may converge together. That is, the at least two points of cutting contact may propagate relative to the body until converged together.

The at least two cutting edges may be defined by two distinct cutting edges. In some embodiments the at least two cutting edges may be defined by separate regions of a single cutting edge.

The at least two cutting edges may be aligned substantially obliquely relative to a rotation axis of the ball member.

At least one cutting edge may be generally straight. At least one cutting edge may be curved, for example arcuate.

A recessed cutting region may be defined by a notch extending into the edge region of an associated through bore.

A recessed cutting region may be generally v-shaped, for example defined by a v-shaped notch.

A recessed cutting region may be arcuate, for example.

The bore edge of at least one of the valve seat and ball member may define a single recessed cutting region. The bore edge of at least one of the valve seat and ball member may define at least two recessed cutting regions. In such an arrangement at least two cutting regions may be separated from each other. At least two cutting regions may merge or overlap each other.

A recessed cutting region may comprise a projection, for example a central projection, which may function to pierce the body, for example centrally of the body.

A recessed cutting region may comprise a serrated edge.

The ball valve may comprise one or more inserts located within a recessed cutting region. The insert may define a cutting edge. Such an insert may facilitate easier maintenance and the like. For example, to re-establish a sufficient cutting edge only the insert need be replaced, rather than the entire ball.

The ball member may define a sealing area which cooperates with an appropriate sealing area of the ball seat, at least when the valve is in a closed configuration. The ball seal area is rotationally offset from the ball through bore. The recessed cutting region may be defined within the ball member, wherein said cutting region is recessed towards the sealing area.

The housing may be configured to be secured in-line with a fluid conduit system, wherein the ball seat and ball member may cooperate to control flow along the fluid conduit system. The fluid conduit system may be defined by one or more tubing components, flow equipment such as other valves, flow meters, shear-sub components or the like. The housing may be configured to be secured in-line with a landing string.

The housing may comprise first and second connectors for securing in-line with a fluid conduit system, such as a landing string. At least one of the first and second connectors may comprise a flange connector, such as a bolted flange connector. The first and second connectors may be configured to be secured to a similar component, such as tubing, for example. The first and second connectors may be configured to be secured to different components. For example, one connector may be configured to be secured to tubing, and one connector may be configured to be secured to flow equipment such as another valve or the like.

The housing may comprise a unitary component.

Alternatively, the housing may comprise multiple components.

The housing may comprise an outer housing configured to be mechanically secured in-line with a fluid conduit system and an inner housing located within the outer housing and configured to contain pressure.

The outer housing may be defined as a structural housing. That is, the outer housing may be provided primarily to accommodate mechanical forces, such as axial and bending forces, associated with the fluid conduit system while providing minimal or no pressure containment, for example of internal and/or external pressures. The inner housing may be defined as a pressure housing. That is, the inner housing may be provided primarily for pressure containment, for example of internal and/or external pressures, while providing minimal or no contribution to accommodating mechanical loading associated with the fluid conduit system This arrangement may permit each individual housing to be designed and/or selected to meet more focussed or specific operational requirements.

These divided roles of the first and second housings may provide a number of advantages, such as reduction in wall thickness, weight, costs and the like. In particular, the provision of an outer structural housing and a separate pressure containing inner housing may permit a reduction in the global housing wall thickness to be achieved. That is, as the outer housing is not intended to be pressure containing, the wall thickness of this can be significantly reduced. Furthermore, as the inner housing is intended for pressure containment, and not, for example, to accommodate significant tensile and bending loads, this too can have a minimal wall thickness for its limited function. As such, the combined wall thickness can be reduced relative to a single structure which is designed to be exposed to both mechanical and pressure loading.

Reducing the overall wall thickness of the housing may permit a larger housing inner diameter to be available allowing one or both of the ball seat and ball member to be increased in size. This may be particularly advantageous in permitting a sufficient valve sealing area to be achieved even with the presence of a recessed cutting region. That is, the recessed cutting region may encroach into a sealing area of the ball seat and/or ball member, wherein an increased ball seat and/or ball member, and associated sealing area may permit such encroachment to be accommodated without compromising sealing integrity.

By the outer housing being mechanically secured in-line with a fluid conduit system mechanical forces, such as tensile forces and bending forces, may be transmitted across the outer housing. Such mechanical forces may originate from the fluid conduit system, such as from the weight of the fluid conduit system or the like.

The outer housing may comprise a connection arrangement for permitting mechanical connection with a fluid conduit system. The connection arrangement may comprise first and second connectors for securing in-line with a fluid conduit system. At least one of the first and second connectors may comprise a flange connector. At least one of the first and second connectors may define a preloaded connector. Such preloading may be achieved by use of one or more preloaded bolt connections. Such preloading may permit the point of connection from separating during use, for example due to axial and bending forces. As the inner housing is located internally within the outer housing and does not include any direct mechanical connection with the fluid conduit system, any requirement to provide such a preloaded connector with the inner housing is eliminated. That is, only the connection between the outer housing and the fluid conduit system may require preloading, for example to meet required or preferred industry standards.

The inner housing may be axially contained within the outer housing. In such an arrangement any axial loading experienced by the inner housing, for example due to internal pressures, valve actuation forces and the like may be transferred to the outer housing. The inner housing may be axially contained between first and second connectors of the outer housing.

The ball seat may be axially contained between the inner housing, for example an axial end of the inner housing, and the outer housing, for example a connecting portion of the outer housing. Such an arrangement may provide a simple modular construction, permitting ease of assembly while ensuring sufficient retention of the ball seat within the ball valve. Furthermore, such an arrangement may eliminate the requirement to provide a mechanical connection of the ball seat within the ball valve, providing advantages in terms of, for example, space saving.

The outer housing may comprise an axially extending wall section configured to encapsulate the inner housing. As pressure forces are contained primarily by the inner housing, the wall thickness of the axially extending wall section of the outer housing may be minimised.

The outer housing may define a barrel-type housing.

The outer housing may be split to permit access to install, remove, replace, inspect or the like the inner housing. In one embodiment the outer housing may be longitudinally split, that is, split along its length. The outer housing may comprise at least two housing segments. The housing segments may be hingedly connected together. The housing segments may be configured to be secured together when in a closed configuration. For example, the housing segments may be secured together in a closed configuration when the outer housing is secured to a fluid conduit system, for example via first and second connectors. The housing segments may be secured along a length of separation, for example along the length of the split defined between the different segments. This arrangement may provide or establish appropriate hoop stiffness within the outer housing which may be required to resist bending forces, for example.

The housing segments may be secured together by a bolting arrangement. The bolting arrangement may be provided along one or more sides or regions of separation between different segments.

The housing segments may be secured together via one or more tangential bolts.

Adjacent segments may comprise one or more connecting portions extending at least partially along the length of split defined between the adjacent segments, wherein opposing connecting portions of each segment may be secured together, for example via bolting. A plurality of connecting portions may be provided on each adjacent segment. Axially adjacent connecting portions on a single segment may be separated by a slotted region, such as a laterally extending slot. Such separation between axially adjacent flange portions may permit appropriate redirection of stress around and across this area of connection between segments, for example due to tensile loading.

The housing segments may be secured together via one or more axially extending connecting members, such as a connecting rod, bolt or the like. In such an arrangement adjacent housing segments may comprise interleaving portions which are held together via such an axially extending connecting member.

As the outer housing is not intended to be pressure containing any sealing, or at least any significant sealing arrangements, may not be required between individual housing segments when secured together.

At least a portion of the outer housing may define a generally cylindrical outer profile.

At least a portion of the outer housing may define a generally non-cylindrical outer profile having different dimensions in mutually perpendicular lateral directions. For example, at least a portion of the outer housing may define a generally oval outer profile, elliptical outer profile or the like. Such an arrangement may permit umbilicals or the like to be accommodated between the valve housing and an outer constraining structure, such as an outer pipeline, borehole, casing section, riser or the like.

In some embodiments a connection arrangement, such as a flange connection arrangement of the outer housing may define a non-cylindrical profile.

The outer housing may define one or more axial holes, such as gun drilled holes, which may accommodate fluid communication, for example across the entire length of the housing, to provide hydraulic power to the valve internal components such as actuators or the like.

The inner housing may define a generally cylindrical profile.

The inner housing may be isolated from mechanical connection with a fluid conduit system. For example, the inner housing not be exposed, or may be exposed to a far lower proportion of mechanical loading associated with the fluid conduit system as the outer housing. This lack of connection thus eliminates any requirement for a preloaded connection with the fluid conduit system, for example as may be required or preferred by industry standards. This permits space saving to be achieved, for example in terms of available internal diameter thus allowing larger valve mechanisms and components, such as the ball seat and ball member, to be utilised.

The inner housing may be defined by a pressure containing sleeve.

The inner housing may be arranged to accommodate one or both of the ball seat and ball member. The inner housing may be configured to accommodate a valve actuator. For example, inner housing may define a piston cylinder or the like.

The ball valve may comprise a plurality of respective ball seats and ball members. Such an arrangement may provide a degree of redundancy within the ball valve.

According to a second aspect of the present invention there is provided a method for isolating a fluid conduit system having a body extending internally therethrough, comprising:

-   -   securing a ball valve in-line within the fluid conduit system,         wherein the ball valve comprises a housing, a ball seat arranged         in the housing and a ball member mounted within the housing and         being rotatable relative to the ball seat between open and         closed positions, wherein the ball seat and ball member define         respective through bores each having a bore edge, and wherein         the bore edge of at least one of the valve seat and ball member         defines a recessed cutting region; and     -   rotating the ball member to close the valve and to cut a body         extending at least partially through the valve with the recessed         cutting region.

According to a third aspect of the present invention there is provided a sub sea test tree comprising:

a housing;

-   -   a ball seat arranged in the housing;     -   a ball member mounted within the housing and being rotatable         relative to the ball seat between open and closed positions;     -   wherein the ball seat and ball member define respective through         bores each having a bore edge, and wherein the bore edge of at         least one of the valve seat and ball member defines a recessed         cutting region for cutting a body extending at least partially         through the valve upon closure of the ball member.

The housing may be configured to be located within a Blow Out Preventor (BOP).

According to a fourth aspect of the present invention there is provided a landing string assembly comprising a valve, wherein the valve comprises:

-   -   a housing;     -   a ball seat arranged in the housing;     -   a ball member mounted within the housing and being rotatable         relative to the ball seat between open and closed positions;     -   wherein the ball seat and ball member define respective through         bores each having a bore edge, and wherein the bore edge of at         least one of the valve seat and ball member defines a recessed         cutting region for cutting a body extending at least partially         through the valve upon closure of the ball member.

The valve may define a sub sea test tree.

According to a fifth aspect of the present invention there is provided a valve comprising:

-   -   an outer housing configured to be mechanically secured with a         fluid conduit system;     -   an inner housing located within the outer housing and configured         to contain pressure; and     -   a valve mechanism mounted within the inner housing.

The outer housing may be mechanically secured in-line with a fluid conduit system.

According to a sixth aspect of the present invention there is provided a ball valve comprising:

-   -   a housing;     -   a ball seat arranged in the housing;     -   a ball member mounted within the housing and being rotatable         relative to the ball seat between open and closed positions;     -   wherein a leading edge of at least one of the ball valve and         ball seat comprises a v-shaped notch for cutting a body         extending at least partially through the valve upon closure of         the ball member.

Features defined in relation to one aspect defined above may be associated with any other aspect.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

FIG. 1 illustrates a landing string arrangement which includes features according to embodiments of aspects of the present invention;

FIG. 2 is a cross-sectional view of a ball valve in accordance with an embodiment of the present invention;

FIG. 3 is a perspective view of a ball member which may be utilised in the ball valve of FIG. 2, in accordance with an embodiment of the present invention;

FIG. 4 is a cross-sectional view of the ball member of FIG. 3 shown in combination with an associated ball seat;

FIG. 5 is an top elevational view of the ball member, ball seat and coiled tubing shown in FIG. 4;

FIG. 6 is a perspective view of a ball member and ball seat of a ball valve according to a modified embodiment of the present invention;

FIGS. 7 and 8 are top elevational views of alternative embodiments of a ball member according to the present invention;

FIG. 9 is a perspective view of a split outer housing component of a valve according to an embodiment of the present invention, wherein the split housing component is shown in a closed configuration and coupled within a flowline;

FIG. 10 is a cross-sectional view of a valve assembly which incorporates the split outer housing of FIG. 9;

FIG. 11 is a perspective view of a split outer housing component of a valve according to an alternative embodiment of the present invention, wherein the split housing component is shown in an open configuration; and

FIG. 12 is a top elevational view of a ball valve shown located within a riser, in accordance with a modified embodiment of the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

A landing string assembly 10 is diagrammatically illustrated in FIG. 1, shown in use within a riser 12 and extending between a surface vessel 14 and a subsea wellhead assembly 16 which includes a BOP 18 mounted on a wellhead 20. The use and functionality of landing strings are well known in the art for through-riser deployment of equipment, such as completion architecture, well testing equipment, intervention tooling and the like into a subsea well from a surface vessel.

When in a deployed configuration the landing string 10 extends through the riser 12 and into the BOP 18. While deployed the landing string 10 provides many functions, including permitting the safe deployment of wireline or coiled tubing equipment (not shown) through the landing string and into the well, providing the necessary primary well control barriers and permitting emergency disconnect while isolating both the well and landing string 10.

Wireline or coiled tubing deployment may be facilitated via a lubricator valve 22 which is located proximate the surface vessel 14.

Well control and isolation in the event of an emergency disconnect is provided by a suite of valves, typically ball valves, which are located at a lower end of the landing string 10 inside the BOP. The valve suite includes a lower valve assembly called the subsea test tree (SSTT) 24 which provides a safety barrier to contain well pressure, and also functions to cut any wireline or coiled tubing which extends through the landing string 10. The valve suite also includes an upper valve assembly called the retainer valve 26 which isolates the landing string contents and can be used to vent trapped pressure from between the retainer valve 26 and SSTT 24. A shear sub component 28 extends between the retainer valve 26 and SSTT 24 which is capable of being sheared by shear rams 30 of the BOP 18 if required. A slick joint 32 extends below the SSTT 24 which facilitates engagement with BOP pipe rams 34.

The landing string 10 may include an interface arrangement for interfacing with other oil filed equipment. For example, in the present embodiment the landing string 10 includes a tubing hanger 36 at its lowermost end which engages with a corresponding tubing hanger 38 provided in the wellhead 20. When the landing string 10 is fully deployed and the corresponding tubing hangers 36, 38 are engaged, the weight of the lower string (such as a completion, workover string or the like which extends into the well and thus not illustrated) becomes supported through the wellhead 20. However, during deployment of the lower string through the riser 12 all the weight and other forces associated with the lower string must be entirely supported through the landing string 10. Furthermore, when deployed a degree of tension is conventionally applied to the landing string 10, for example to prevent adverse compressive forces being applied, for example due to the weight of the landing string 10, which can be significant in deep water. The landing string 10 must thus be designed to accommodate significant in-service loadings, such as the global tension and bending loads from a supported lower string. Such in-service loadings, which may also include valve actuation loading, internal and external pressures and the like, must be accommodated across the various valve assemblies, such as the SSTT 24. It is therefore necessary to design the valve housings and appropriate end connections to be capable of accommodating the global applied tension, bending loads, valve actuation loading, pressures and the like.

A cross sectional view of a ball valve in accordance with an embodiment of the present invention is shown in FIG. 2. The ball valve may be provided for various functions, but for the purposes of the present description the ball valve may define a SSTT 24 of the landing string 10 shown in FIG. 1. It should be noted that although the SSTT 24 is illustrated in FIG. 1 as a dual ball valve, the arrangement shown in FIG. 2 is a single ball valve assembly for purposes of clarity.

The ball valve 24 includes a housing, generally identified by reference numeral 40 which is secured between the upper shear sub component 28 and the lower slick joint 32. As such, the ball valve 24 is installed in-line with the landing string 10 which can be considered to be a fluid conduit system. The housing 40 accommodates a ball seat 42 and a ball member 44, wherein the ball member 44 is rotatable about axis 46 to selectively close the ball valve 24 and control flow through the landing string. In the embodiment shown the ball member 44 is rotatable in the direction of arrow 48 to close the ball valve 24. The ball seat 42 and ball member 44 define respective through bores 50, 52 which when aligned define a flow path through the valve 24 and when misaligned (as shown in FIG. 2) prevent or restrict flow through the valve. When the ball member 44 is closed a sealing area 54 is defined between the ball seal 42 and ball member 44.

As will be discussed in further detail below, a leading edge 56 of the ball member 44 and/or ball seat 42 is configured to cut through a body (not shown), such as wireline, coiled tubing or the like which extends through the valve 24 and landing string 10 (FIG. 1) upon closure of the ball member 44.

As will also be discussed in further detail below, the housing 40 comprises an outer housing 60 configured to be mechanically secured in-line with the landing string 10 (FIG. 1), and an inner housing 62 located within the outer housing 60 and configured to contain pressure. The outer housing component 60 comprises a thin-walled, non-pressure containing cylindrical portion 63 which extends between axially opposing end flange connectors 64, 66 which are configured to be secured to flange components 68, 70 of the shear sub 28 and slick joint 32, respectively. In such an arrangement the outer housing 60 may be defined as a structural housing. That is, the outer housing 60 may be provided primarily to accommodate mechanical forces, such as axial and bending forces, associated with the landing string 10 and any supported lower string while providing minimal or no pressure containment, for example of internal and/or external pressures.

The inner housing 62 comprises a generally cylindrical portion or sleeve and does not include any mechanical connection to the landing string 10 (FIG. 1). In such an arrangement the inner housing 62 may be defined as a pressure housing. That is, the inner housing 62 may be provided primarily for pressure containment, for example of internal and/or external pressures, while providing minimal or no contribution to accommodating mechanical loading associated with the landing string 10 and/or supported lower string.

This split role arrangement may permit each individual housing 60, 62 to be designed and/or selected to meet more focussed or specific operational requirements, providing a number of advantages, such as permitting a reduction in the global wall thickness of the housing which can increase the available internal housing diameter.

The ball valve further includes an actuator assembly, generally identified by reference numeral 72 for use in actuating the ball member 44 to rotate relative to the ball seat 42 between open and closed positions. In the present example the actuator assembly 72 comprises a piston arrangement.

Various forms of ball member 44 and ball seat 42 may be provided within the scope of the present invention. Some exemplary embodiments are described below with reference to FIGS. 3 to 8.

Reference is initially made to FIGS. 3 and 4. FIG. 3 shows a perspective view of a ball member, in this case identified by reference numeral 44 a, according to an exemplary embodiment of the present invention, and FIG. 4 shown a cross-sectional view of the ball member 44 a of FIG. 3 in combination with an embodiment of a ball seat, in this case identified by reference numeral 42 a. Ball member 44 a and seat 42 a have many features in common with ball member 44 and seat 42 shown in FIG. 2 and as such like features share like reference numerals, suffixed with the letter “a”.

The ball member 44 a defines a through bore 52 a having a bore edge 74, wherein a leading edge 56 a defines a recessed cutting region 76 which is configured to receive and cut through a body, such as coiled tubing 78, shown in broken outline in FIG. 4 extending through the through bore 52 a of the ball member 44 a and a through bore 50 a of the ball seat 42 a. That is, rotation of the ball member 44 a towards a closed position causes the coiled tubing 78 to become engaged between the edge of the ball seat 42 a and the recessed cutting region 76 of the ball member 44 a, with further rotation effecting cutting of the coiled tubing 78 primarily by a shearing action. The ball member 44 a includes a slotted region 80 which accommodates the lower portion of the coiled tubing 78 during rotation of the ball member 44 a.

The recessed cutting region 76 encroaches into the sealing area 54 a which is defined between the ball member 44 a and ball seat 42 a. In some embodiments the recessed cutting region may define a relatively shallow recess such that sealing area 54 a may not be compromised. However, in other embodiments the ability to utilise a thinner walled housing 40 by use of separate outer and inner housings 60, 62 (having different roles, namely structural and pressure containing) facilitates use of a larger ball member 44 a and ball seat 42 a such that even with the presence of the recessed cutting region 76 the sealing area 54 a may be sufficiently large to retain sealing integrity.

In the present embodiment the recessed cutting region 76 is generally v-shaped. Such a v-shaped cutting region 76 is also shown in FIG. 5 (reference to which is also made) which is a top elevational view of the ball seat 42 a and ball member 44 a. Such a profile defines two cutting edges 82, 84 which provide simultaneous initial cutting into separate regions of the tubing 78. In this way, during initial contact two points of cutting contact are created which are offset from a central region of the tubing 78 and which propagate together as cutting continues. This arrangement may permit the force of cutting to be divided between the different points of cutting contact provided by each cutting edge 82, 84, assisting to prevent collapsing of the tubing 78 which the present inventors have discovered can render cutting very difficult. Also, this arrangement may require less torque through the ball member 44 a to cut the tubing 78. Such reduced loading is anticipated to reduce damage to the components of the ball valve which may assist in preventing or reducing any damage to sealing regions, such as sealing area 54 a.

As illustrated most clearly in FIG. 5, in the present embodiment, the leading edge 86 of the ball seat 42 a does not include any recessed region. However, in other embodiments, the ball seat may also (or alternatively) include a recessed region. Such an embodiment is illustrated in FIG. 6 which is a perspective view, from below, of a ball seat 42 b and ball member 44 b which both include recessed cutting regions 88, 90.

In the exemplary embodiments described above the recessed cutting region is generally v-shaped. However, other arrangements are possible. For example, a ball member 44 c (or a corresponding ball seat) may include a generally arcuate recessed region 92 as shown in FIG. 7. Furthermore, in the exemplary embodiments described above a single recessed cutting region is provided. However, in other arrangements multiple recessed regions may be provided. For example, a ball member 44 c (or corresponding ball seat) may include a pair of (or more) recessed regions 94 as shown in FIG. 8. In such an embodiment a projection 96 may be defined between each recessed region 94 which may function to pierce a body, such as coiled tubing, to assist in initiating cutting while minimising adverse collapse or the like. Such a projection may be provided within embodiments including a single recess.

A perspective view of the ball valve 24 illustrated in FIG. 2 is shown in FIG. 9, reference to which is now made, along with FIG. 10 which shows a further cross-sectional view of the ball valve 24 with the ball member 44 and actuator 72 removed for clarity.

As described above, the housing 40 of the valve 24 includes an outer housing 60 and a separate inner housing 62, wherein the outer housing 60 includes opposing flange connectors 64, 66 which are secured to the respective flange components 68, 70 of the shear sub 28 and slick joint 32. Each flange connection 64, 68 and 66, 70 is made via a plurality of bolts 100, wherein one or more of the bolts 100 may be pre-tensioned to provide a degree of preloading through the connections.

The inner housing 62 is axially retained between the flange connectors 64, 66 of the outer housing 60. Furthermore, the ball seat 42 is interposed between the upper flange connector 64 and the upper end of the inner housing 62.

The inner housing 62 defines a unitary cylindrical component, whereas the outer housing 60 is longitudinally split along a line of separation 102 such that the outer housing 60 is formed from two half segments 104, 106. Referring also to FIG. 11, this split arrangement permits the outer housing 60 to be opened to provide access to install, inspect, repair, replace or the like the inner housing 62 and other components, such as the ball seat 42. Splitting a housing of a valve is generally not attempted in the art. However, the present invention permits the outer housing 60 to be split as this does not need to provide any sealing or pressure retaining function, which instead is provided by the unitary inner housing 62.

The segments 104, 106 are hinged together along one side 108 and once closed may be retained closed upon connection of the respective flange connectors 64, 66 to the flange components 68, 70 of the shear sub 28 and slick joint 32. Additionally, a longitudinal connecting arrangement 110 is provided which longitudinally secures the segments 104, 106 together when closed. In an alternative embodiment no hinge connection may be provided and instead both sides may be bolted to secure together the different segments 104, 106. Providing such a longitudinal connection arrangement 110 establishes appropriate hoop stiffness within the outer housing 60 which may be required to resist bending forces, for example.

The longitudinal connection arrangement 110 may be provided in a number of forms. In this respect one such form is illustrated in FIG. 9 (identified by reference numeral 110 a), whereas an alternative form is illustrated in FIG. 11 (identified by reference numeral 110 b).

The longitudinal connection arrangement 110 a of FIG. 9 comprises a plurality of tangential-type bolts or cap screws 112 which extend through respective flange fingers or ribs 114 on one housing segment 106 and engage threaded holes (not illustrated) in the opposing housing segment 104. Each adjacent flange finger or rib 114 is separated by a slotted region 116. This geometry assist to redirect stress along this region of connection to, for example, prevent high stresses at the locations of the cap screws 112 during tensile loading.

The longitudinal connection arrangement 110 b illustrated in FIG. 11 comprises a plurality of interleaving components 118 on each segment which are interleaved with each other when the segment halves 104, 106 are closed. Each interleaving component 118 comprises an axially extending bore 120 which become aligned when the segment halves 104, 106 are closed. An elongate connecting member 122 is provided which is received within the aligned bores 120 to thus secure the segment halves 104, 106 together.

In the embodiments described above, such as with reference to FIGS. 2 and 9 to 11, the outer housing defines a generally cylindrical outer profile. However, in other embodiments a non-cylindrical outer profile may be provided, as illustrated in FIG. 12. In this embodiment a valve, generally identified by reference numeral 124, includes a split outer housing 160 and a unitary inner housing 162, in a similar manner to the embodiments described above for similar reasons. However, in the present embodiment the outer housing 160 defines a generally oval outer profile. This arrangement permits other components, such as the illustrated umbilical 123 to be accommodated between the valve 124 and an outer constraining component, such as a riser 12.

It should be understood that the embodiments described herein are merely exemplary and that various modifications may be made thereto without departing form the scope of the present invention. For example, the disclosed valve embodiments are not solely for use within a landing string, and may be used in many other applications as would be understood by a person of skill in the art. Furthermore, the multiple component housing arrangement may also be used in combination with different valve types, and is not limited solely for use in ball valve applications, although defined and specific advantages do exist in such ball valve applications. 

1. A ball valve comprising: a housing; a ball seat arranged in the housing; a ball member mounted within the housing and being rotatable relative to the ball seat between open and closed positions; wherein the ball seat and ball member define respective through bores each having a bore edge, and wherein the bore edge of at least one of the valve seat and ball member defines a recessed cutting region for cutting a body extending at least partially through the valve upon closure of the ball member.
 2. The ball valve according to claim 1, wherein the respective through bores of the ball seat and ball member define a flow path through the valve, wherein the ball member is rotated relative to the ball seat to misalign the respective through bores to prevent or restrict flow through the valve, and is rotated relative to the ball seat to align the respective through bores to permit or increase flow through the valve.
 3. The ball valve according to claim 1, defining or forming part of at least one of a Subsea Test Tree (SSTT), a retainer valve and a lubricator valve.
 4. The ball valve according to claim 1, wherein the recessed cutting region is configured to cut an elongate body including at least one of tubing, coiled tubing, wireline, slickline and a tool string.
 5. The ball valve according to claim 1, wherein both the ball seat and ball member define a recessed cutting region.
 6. The ball valve according to claim 1, wherein only one of the ball seat and ball member define a recessed cutting region.
 7. The ball valve according to claim 6, wherein only the ball member defines a recessed cutting region.
 8. The ball valve according to claim 1, wherein a recessed cutting region is recessed relative to an associated through bore.
 9. The ball valve according to claim 1, wherein a recessed cutting region defines a cutting edge.
 10. The ball valve according to claim 1, wherein a recessed cutting region defines at least two cutting edges to permit simultaneous cutting into separate regions of a body at least upon initial contact with the body.
 11. The ball valve according to claim 10, wherein the cutting edges define respective points of cutting contact with a body during cutting thereof.
 12. The ball valve according to claim 11, wherein during initial contact with a body the at least two points of cutting contact are offset from a central region of the body, and during cutting the at least two points of cutting contact with the body propagate relative to the body until converged together.
 13. The ball valve according to claim 10, wherein the at least two cutting edges are defined by two distinct cutting edges.
 14. The ball valve according to claim 10, wherein the at least two cutting edges are defined by separate regions of a single cutting edge.
 15. The ball valve according to claim 10, wherein the at least two cutting edges are aligned substantially obliquely relative to a rotation axis of the ball member.
 16. The ball valve according to claim 1, wherein a recessed cutting region is defined by a v-shaped notch.
 17. The ball valve according to claim 1, wherein the bore edge of at least one of the valve seat and ball member defines a single recessed cutting region.
 18. The ball valve according to claim 1, wherein the bore edge of at least one of the valve seat and ball member defines at least two recessed cutting regions.
 19. The ball valve according to claim 1, wherein a recessed cutting region comprises a projection to pierce a body.
 20. The ball valve according to claim 1, wherein the ball member defines a sealing area which cooperates with an appropriate sealing area of the ball seat, at least when the valve is in a closed configuration.
 21. The ball valve according to claim 20, wherein a recessed cutting region is defined within the ball member, wherein said cutting region is recessed towards the sealing area.
 22. The ball valve according to claim 1, wherein the housing is securable in-line with a fluid conduit system, wherein the ball seat and ball member cooperate to control flow along the fluid conduit system.
 23. The ball valve according to claim 1, wherein the housing is securable in-line with a landing string.
 24. The ball valve according to claim 1, wherein the housing comprises first and second connectors for securing in-line with a fluid conduit system.
 25. The ball valve according to claim 24, wherein at least one of the first and second connectors comprises a flange connector.
 26. The ball valve according to claim 1, wherein the housing comprises an outer housing configured to be mechanically secured in-line with a fluid conduit system and an inner housing located within the outer housing and configured to contain pressure.
 27. The ball valve according to claim 26, wherein the outer housing comprises a connection arrangement for permitting mechanical connection with a fluid conduit system.
 28. The ball valve according to claim 27, wherein the connection arrangement comprise first and second connectors for securing in-line with a fluid conduit system.
 29. The ball valve according to claim 28, wherein at least one of the first and second connectors comprises a flange connector.
 30. The ball valve according to claim 28, wherein at least one of the first and second connectors defines a preloaded connector.
 31. The ball valve according to claim 26, wherein the inner housing is axially contained within the outer housing.
 32. The ball valve according to claim 26, wherein the ball seat is axially contained between the inner housing and the outer housing.
 33. The ball valve according to claim 26, wherein the outer housing comprises an axially extending wall section to encapsulate the inner housing.
 34. The ball valve according to claim 26, wherein the outer housing is split.
 35. The ball valve according to claim 26, wherein the outer housing is longitudinally split.
 36. The ball valve according to claim 26, wherein the outer housing comprises at least two housing segments.
 37. The ball valve according to claim 36, wherein the housing segments are securable together when in a closed configuration.
 38. The ball valve according to claim 37, wherein the housing segments are secured together in a closed configuration when the outer housing is secured to a fluid conduit system.
 39. The ball valve according to claim 37, wherein the housing segments are secured along a length of separation.
 40. The ball valve according to claim 37, wherein the housing segments are secured together by a bolting arrangement.
 41. The ball valve according to claim 36, wherein adjacent segments comprise one or more connecting portions extending at least partially along the length of split defined between the adjacent housing segments, wherein opposing connecting portions of each segment are secured together.
 42. The ball valve according to claim 26, wherein at least a portion of the outer housing defines a generally cylindrical outer profile.
 43. The ball valve according to claim 26, wherein at least a portion of the outer housing defines a non-cylindrical outer profile having different dimensions in mutually perpendicular lateral directions.
 44. The ball valve according to claim 26, wherein the inner housing is isolated from mechanical connection with a fluid conduit system.
 45. The ball valve according to claim 1, comprising a plurality of respective ball seats and ball members.
 46. A method for isolating a fluid conduit system having a body extending internally therethrough, comprising: securing a ball valve in-line within the fluid conduit system, wherein the ball valve comprises a housing, a ball seat arranged in the housing and a ball member mounted within the housing and being rotatable relative to the ball seat between open and closed positions, wherein the ball seat and ball member define respective through bores each having a bore edge, and wherein the bore edge of at least one of the valve seat and ball member defines a recessed cutting region; and rotating the ball member to close the valve and to cut a body extending at least partially through the valve with the recessed cutting region. 